Radio frequency identification tagging

ABSTRACT

A RFID tag or label comprises a RFID tag module (comprising an electronic identification circuit and a coupling means) and an antenna structure coupled to the coupling means. The RFID tag module is separate from, separable or arranged to be severable from, the antenna structure. The tag module can be placed in or on an object and the antenna structure in or on packaging material for use with the object. A patch antenna type RFID tag antenna structure has a ground plane spaced from the patch antenna so as to increase the range of the tag. The ground plane is not substantially larger than, and electrically insulated from, the patch antenna. The ground plane is flexible, so the RFID tag structure can be worn by a human, and can be incorporated into a piece of clothing. A RFID antenna structure for use with a tag reader is made flat and robust so that it can be mounted on the ground to be walked upon or driven over. A bi-directional YAGI type RFID tag antenna structure has director elements on two opposite sides so that the YAGI antenna radiates in two opposite directions. An object includes a gain increasing metallic structure for increasing the gain of a RFID tag when placed near the object so as to form a RFID tag antenna structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.12/140,639, filed Jun. 17, 2008, which is a continuation of U.S.application Ser. No. 10/527,736, filed Mar. 14, 2005, which is aNational Phase entry of International Application No. PCT/GB2003/003939,filed Sep. 12, 2003, all of which are hereby incorporated herein intheir entireties by reference.

FIELD OF THE INVENTION

The present invention relates to various aspects of radio frequencyidentification (RFID) tagging. The invention is particularly applicableto passive RFID tags, but can also be applied to powered RFID tags. Insome aspects the invention relates to antenna structures for use in RFIDtagging.

BACKGROUND OF THE INVENTION

Passive RFID tags which operate in the UHF band (860 to 920 MHz) areknown in the art. Known RFID tags comprise a RFID integrated circuit ora RFID tag module which is attached to an antenna, which can be adipole, folded dipole, loop or patch antenna. In many situations it isdesirable to use passive RFID tags for tagging objects or items such asproducts being sold in a supermarket, or animals or humans. The passiveRFID tag can then be used, together with a tag reader, to detect thepassage or presence of the tagged object, animal or human in a doorway,portal or similar. However, with currently permitted radio power levelsunder radio regulations in many jurisdictions the operating or readingrange of standard tags is 70 cm or less, which limits the size of anydoorway or portal. Furthermore, the physical orientation of the tag canlimit the ability of a RFID reader to successfully read the tag.

In some aspects the present invention aims to provide a taggingtechnique which enables communication with a RFID tag over a reasonabledistance whilst respecting other concerns such as privacy concerns andcomfort. Other aims will be apparent from the description of preferredembodiments.

BRIEF SUMMARY OF THE INVENTION

In one aspect the present invention provides a Radio FrequencyIdentification (RFID) tag or label comprising:

a RFID tag module comprising an electronic identification circuit and acoupling means; and

an antenna structure coupled to the coupling means,

wherein the RFID tag module is separate from, separable or arranged tobe severable from, the antenna structure.

Typically, the coupling means would be a small antenna connected to, orintegral with, the electronic identification circuit, whereas theantenna structure can be a larger metallic structure. The antennastructure can, for example, comprise a conductive wire which is arrangedparallel and in proximity to the coupling means of the tag module.

Taking the tagging of a shirt in a shop as an example, according to theabove technique, the shirt can be tagged with a very small tag module(having a short operating range, e.g. a few centimetres). An antennastructure such as a metallic foil can be provided on or in the packagingof the shirt, i.e. separate from the shirt. The antenna structureeffectively increases the operating range of the tag module, i.e. itenables the tag to be read over a larger distance (e.g. a few metres).This makes the tag suitable for stock control or theft prevention. Whenthe packaging is removed by the customer the antenna structure isseparated from the shirt, but the small tag module remains in the shirt.The tag module can then no longer be read over the larger distance ofe.g. a few metres, but it can still be read over the shorter distance ofe.g. a few cms.

Since the tag module is very small its presence in the shirt (which maye.g. be integrated into the collar) does not affect the wearing comfort.On the other hand the fact that the tag module remains in the shirtmeans that the tag module can still be read once the packaging has beenremoved (e.g. for guarantee purposes), albeit over the smaller range.Stock control and theft prevention are then no longer necessary.

This technique also addresses the concerns of privacy campaigners. Sinceafter separation of the antenna structure from the tag module theoperating range of the tag module is very limited it is impossible tomisuse the tagged shirt by tracking the movement of an individualwearing the tagged shirt.

In many situations the antenna structure would be separate or separablefrom the remainder of the tag, i.e. the tag module. However, it can alsoinitially be connected to, or integral with, the tag module, in whichcase a specific provision will have been made to permit the antennastructure to be severed from the tag module during normal use. Thiscould take the form of a preferred line of fracture in the material(which may or may not be conductive) linking the antenna structure andthe remainder of the tag.

The antenna structure may also comprise a metal rod or wire. In someembodiments the rod or wire is straight, but it can alternatively bemultidimensional, i.e. not straight. This may improve the ability of thetag module to be communicated with from different directions. Theantenna structure may also comprise a plurality of antenna elements,e.g. several rods or wires. Again, the ability of the tag module to becommunicated with from different directions can be improved by providingseveral rods or wires which are substantially non-parallel. Each wire orrod is then “responsible” for covering a particular space angle.

Depending on the specific requirements, the RFID tag module can beconstructed such that it can substantially not be communicated with whenit is not coupled to the antenna structure. It could, for example,consist of the electronic identification circuit and a galvanicconnection to the antenna structure (which is not part of the tagmodule). Once the connection between the circuit and the antennastructure is severed (e.g. by breaking the galvanic connection) the tagcan not be communicated with using RF technology, although it may bepossible to reconnect (i.e. galvanically connect) the tag module toanother (or the original) antenna structure to restore the ability tocommunicate with the tag.

Alternatively, the RFID tag module may be constructed such that it canbe communicated with (by RF technology) when it is not coupled to theantenna structure, i.e. it can, for example, have its own antenna (whichmay be integrated into the circuit). However, in the preferredembodiment the (external) antenna structure enhances the ability tocommunicate with the tag module. For example, the distance over whichthe module can be communicated with when it is not coupled to the(external) antenna structure could be d0, the distance over which it canbe communicated with when it is coupled to the (external) antennastructure could be d1, wherein d1 is substantially larger than d0.

The “communication” with the RFID tag module can take various forms suchas:

-   -   reading the identity of the tag    -   writing the identity of the tag    -   accessing the data in the tag by reading or writing    -   modifying the state of the tag's state machine or registers or    -   arbitrating a plurality of tags.

The tag module on its own may have a first operating frequency. When theantenna structure is coupled to the coupling means the RFID tag or labelmay have a second operating frequency, which may be different from thefirst operating frequency, i.e. the antenna structureinfluences/determines the operating frequency of the tag or label.

In another aspect the present invention extends to an object for usewith a first Radio Frequency Identification (RFID) tag module, theobject comprising an antenna structure which is integral with, orattached to, the object and which is arranged

to improve the ability to communicate with the first RFID tag module,and/or

to increase the range over which the first RFID tag module can becommunicated with, and/or

to improve the ability to communicate with the first RFID tag module inmultiple directions,

when the first RFID tag module is used in combination with the object soas to form a first RFID tag or label.

The object can be packaging material, e.g. a piece of cardboard forsupporting a folded shirt, to which cardboard an antenna structure (e.g.metal foil of particular dimensions) has been attached, or which isintegral with such an antenna structure.

Alternatively, the object may comprise a transport means such as acontainer or a pallet. The antenna structure of the transport meansenables or improves communication with items which have been providedwith a RFID tag module and which are to be transported by the transportmeans.

Preferably, the object comprises a second RFID tag module which iscoupled to the antenna structure, so as to form a second RFID tag orlabel. In other words, the object has its own “stand alone” tag, whilstalso performing its function of enabling or improving communication withthe tag module of any items to be transported by the object.

Such an arrangement is of particular use in connection with re-usable orreturnable containers, pallets or clothes rails etc, whose movements canbe tracked, as well as the movements of the items in the containers oron the pallets or clothes rails.

Preferably, the antenna structure of the object can be used as antennastructure for several tag modules.

In another aspect the present invention provides a method ofmanufacturing a RFID tag or label, comprising:

providing a RFID tag module comprising an electronic identificationcircuit and a coupling means; and

coupling an antenna structure to the coupling means,

wherein the RFID tag module is separate from, separable or arranged tobe severable from, the antenna structure.

In another aspect the present invention provides a method of operating aRadio Frequency Identification (RFID) system, comprising:

providing a RFID tag in which a RFID tag module is coupled to an antennastructure; and

separating or severing the RFID tag module from the antenna structure.

In another aspect the present invention provides a Radio FrequencyIdentification (RFID) system comprising:

at least one Radio Frequency Identification (RFID) tag or labelcomprising:

-   -   a RFID tag module comprising an electronic identification        circuit and a coupling means; and    -   an antenna structure coupled to the coupling means, and

at least one RFID communication means,

wherein the RFID tag module is separate from, separable or arranged tobe severable from, the antenna structure.

The RFID communication means may, for example, comprise a RFID reader orany other device which is suitable for performing the various forms ofcommunication with the tag module via the antenna structure which areidentified above.

Preferably, the RFID tag module can be communicated with by means of afirst said RFID communication means when the antenna structure iscoupled to the coupling means, and can be communicated with by means ofa second said RFID communication means when the antenna structure is notcoupled to the coupling means, but cannot be communicated with by meansof the first said RFID communication means when the antenna structure isnot coupled to the coupling means. Using again the above example of theshirt, the first RFID communication means may, for example, comprise aRFID reader for guarantee claims (i.e. operational only over a shortrange), whereas the second reader may, for example, comprise a RFIDreader (operational over a larger range) placed at a doorway or portalfor stock control or theft prevention.

In another aspect the present invention provides an antenna structurefor use in a RFID tag or label comprising a RFID tag module and a saidantenna structure, the antenna structure comprising:

a metallic material of such characteristics that, when brought into acoupling relationship with the RFID tag module,

-   -   it improves the ability to communicate with the RFID tag or        label and/or    -   it increases the operating range of the RFID tag or label and/or    -   it improves the ability to communicate with the RFID tag or        label in multiple directions,

wherein the antenna structure is not galvanically connected to the RFIDtag module.

Preferably, the antenna structure is connected to, or integral with,packaging material.

In another aspect the present invention provides an object comprising aRadio Frequency Identification (RFID) tag module which is integral with,or attached to, the remainder of the object and which is for coupling toa suitable antenna structure so as to form a RFID tag or label, wherein,when the RFID tag module is coupled to a suitable antenna structure,

the ability to communicate with the RFID tag module is improved, and/or

the range over which the RFID tag module can be communicated with isincreased, and/or

the ability to communicate with the RFID tag module in multipledirections is improved,

when compared with a situation in which the RFID tag module is notcoupled to a suitable antenna structure.

Preferably, the RFID tag module is in such a way integral with, orattached to, the remainder of the object that it cannot be connected toa said antenna structure by a galvanic connection. Using again the aboveexample of the shirt, the RFID tag module can be incorporated into thecollar of the shirt (the object) so that the module is completelysurrounded by the material of the shirt. As the tag module is notaccessible from the outside it is impossible (during normal use of theshirt) to establish a galvanic connection with the tag module.

In some aspects the present invention aims to increase the range ofpassive RFID tags. U.S. Pat. No. 6,278,413 discloses a RFID tag withdriven antenna element which is provided with a reflector element 38 onone side of the driven antenna element 18 and a director element 36 onthe other side of the driven antenna element (see for example FIG. 27).The driven antenna element, the reflector element and the. directorelement are mounted on a substrate, which substrate can be folded orformed into a roll. It will be appreciated that, in particular in thefolded state, this structure is prone to damage or detuning.

U.S. Pat. No. 6,215,402 discloses a RFID tag including a patch antennaand a ground plane spaced from the patch antenna.

The present inventors have appreciated that the RFID tag disclosed inU.S. Pat. No. 6,215,402 is relatively large, due to the fact that theground plane is substantially larger than the patch antenna of the tagstructure. The present inventors have found that, surprisingly, theground plane does not need to be substantially larger than the patchantenna without significant loss of range.

Hence, in another aspect the present invention provides a RadioFrequency Identification (RFID) tag antenna structure comprising: apatch antenna; and a ground plane spaced from the antenna, wherein thearea spanned by the ground plane is not substantially larger than thearea spanned by the patch antenna.

Due to its reduced size the RFID tag structure can be more easily usedto tag objects, and when used to tag humans or animals it can be wornwith more comfort.

Pursuant to a related aspect the inventors have researched how thewearing comfort of a RFID tag structure can be increased. He has foundthat the ground plane can be made from a flexible material, such as ametallic mesh or a foil.

In another aspect the present invention provides a Radio FrequencyIdentification (RFID) tag antenna structure comprising: a patch antenna;and a ground plane spaced from the antenna, wherein the ground plane isflexible.

In particular if the ground plane is made from a mesh it canconveniently be incorporated into a piece of clothing, therebyincreasing the wearing comfort. This aspect is also providedindependently.

In another aspect the present invention provides a Radio FrequencyIdentification (RFID) tagging method comprising incorporating a patchantenna and a ground plane spaced from the antenna into a piece ofclothing. This is of course not to be confused with the tagging ofclothes in a shop, where the tag is provided externally of the piece ofclothing and connected thereto by a flexible piece of plastic materialor similar.

In another aspect the present invention provides an object for use witha Radio Frequency Identification (RFID) tag, the object comprising ametallic structure which is integral with the rest of the object andwhich is arranged to increase the efficiency of a said RFID tag whenused in combination with the object so as to form a Radio FrequencyIdentification (RFID) tag antenna structure. The metallic structure may,for example, comprise a ground plane for a patch antenna or one or morestrips of metal foil or metal rods.

According to this aspect a standard RFID tag (i.e. without gainincreasing metal structures such as a ground plane or director and/orreflector elements) can be mounted to the object to be tagged. Thismeans that the standard RFID tag only needs to be handled once, which isless when compared with a technique according to which a ground plane orreflector/director element is first mounted to the RFID tag and then theRFID tag and the ground plane or director/reflector element are mountedto the object. Further, in particular if the metallic structure ismoulded into the material of the object, there are fewer parts whichstand proud of the surface of the object.

In another aspect the present invention provides a Radio FrequencyIdentification (RFID) antenna structure comprising: a patch antenna; anda ground plane spaced' from the antenna, wherein the patch antenna issupported and strong enough so as to withstand substantial forces in adirection perpendicular to its surface.

This is of particular use if a RFID antenna structure is required whichcan be placed on the ground or a floor, for example in order to detect,when connected to a tag reader, the passage of an object, a human or ananimal across the ground or floor.

By altering the size of the ground plane or second plane the radiationpattern can be varied.

According to U.S. Pat. No. 6,215,402 the patch antenna of the RFID tagand the ground plane are electrically connected via a circuit includinga quarterwave transformer. The present inventors have found that, infact, no electrical connection between the ground plane and the antennais necessary.

In another aspect the present invention provides a Radio FrequencyIdentification (RFID) tag antenna structure comprising: a patch antenna;and a ground plane spaced from the antenna, wherein the ground plane iselectrically insulated from the patch antenna.

Pursuant to a further aspect of the invention the present inventors havefound that a multi-element antenna similar in construction to a YAGItype RFID tag antenna structure can be made to radiate in two oppositedirections. Whilst according to U.S. Pat. No. 6,278,413 a reflectorelement (of the same length as the driven antenna element) is placed onone side of the driven antenna element, and a (shorter) director elementis placed on the opposite side of the driven element, the inventors havefound that by using two director elements on opposite sides of thedriven antenna element the RFID tag can be made to radiate in oppositedirections.

It is usual for YAGI antenna elements to be shortened as their distancefrom the active element is increased. This is not necessarily the casewith the multi-element antenna structure disclosed herein. In fact, itis preferred that all antenna elements on either side of the activeelement have the same length.

Accordingly, in another aspect the present invention provides amulti-element Radio Frequency Identification (RFID) tag antennastructure comprising: a RFID tag; an antenna element driven by the RFIDtag; and at least two director elements, at least one on each of twoopposite sides of the driven antenna element, whereby the multi-elementantenna is able to radiate in two opposite directions.

Apparatus aspects corresponding to method aspects disclosed herein arealso provided, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Some preferred embodiments of the invention will now be described by wayof example only and with reference to the accompanying drawings, inwhich:

FIG. 1 shows a perspective view of a passive RFID tag antenna structureaccording to an embodiment of the present invention;

FIG. 2 shows a perspective view of a RFID tag antenna structure forconnection to a tag reader in accordance with an embodiment of thepresent invention;

FIG. 3 shows a particular use of the antenna structure shown in FIG. 2;

FIG. 4 shows a YAGI type antenna structure for use in an embodiment ofthe present invention;

FIG. 5 shows an object with integral gain increasing metallic structureaccording to an embodiment of the present invention; and

FIG. 6 shows a bi-directional YAGI antenna structure according to anembodiment of the present invention.

FIG. 7 shows a perspective view of a RFID tag with separate tag moduleand antenna structure according to an embodiment of the presentinvention;

FIG. 8 shows a perspective view of a RFID tag with separate tag moduleand antenna structure according to an embodiment of the presentinvention;

FIG. 9 shows a perspective view of a RFID tag with separate tag moduleand antenna structure according to an embodiment of the presentinvention;

FIG. 10 shows a perspective view of a crate incorporating an antennastructure according to an embodiment of the present invention;

FIG. 11 shows a perspective view of a container incorporating a slotantenna structure and items placed within the container according to anembodiment of the present invention;

FIG. 12 shows a perspective view of a multiple-element slot antennastructure according to an embodiment of the present invention;

FIG. 13 shows a multidimensional wire antenna structure according to anembodiment of the present invention;

FIG. 14 shows a RFID tag with a preferred line of fracture according toan embodiment of the present invention; and

FIG. 15 shows a RFID tag with a preferred line of fracture according toan embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a first embodiment of a passive RFID tagantenna structure according to the present invention is shown. The RFIDtag antenna structure 10 comprises a patch antenna 20 with a RFID tagintegrated circuit 30. A ground plane 40 of metallic material isprovided, which extends parallel to the patch antenna 20. The areaspanned by the ground plane 40 is only slightly larger than the areaspanned by the patch antenna 20. A dielectric 50 fills the space betweenthe patch antenna 20 and the ground plane 40.

Whilst a relatively large absorbing body such as a bucket of water or ahuman body would absorb most of the RF power of the patch antennawithout the ground plane when brought near the absorbing body, theground plane 40 effectively shields the patch antenna 20 againstabsorbing bodies “behind” the ground plane 40, even if such absorbingbodies are much larger than the ground plane 40. Since the ground plane40 is only slightly larger than the patch antenna 20 the overalldimensions of the RFID tag antenna structure are only slightly largerthan those of the patch antenna 20.

According to some embodiments of the present invention the ground plane40 can be made from a flexible material such as a mesh or a foil. Thisenables the RFID tag antenna structure to be worn by a human or animalwith more comfort when compared with a RFID tag antenna structure with arigid ground plane. The ground plane 40 and/or the patch antenna 20 canthen be incorporated into a piece of clothing. For example, the entireRFID tag antenna structure can be sandwiched between two layers offabric. Alternatively, a layer of fabric can be used as the dielectric50, i.e. the layer of fabric is sandwiched between the patch antenna 20and the ground plane 40.

In trials by the present inventors good results (in terms of range) havebeen obtained by using a ground plane which spans an area which is lessthan 2.5 times the area spanned by the patch antenna, less than 2 times,less than 1.5 times or even less than 1.2 times the area spanned by thepatch antenna.

Referring now to FIG. 2, the RFID antenna structure 110 for connectionto a tag reader (not shown) has a structure similar to the RFID tagantenna structure 10 of FIG. 1. The RFID antenna structure 110 comprisesa patch antenna 20, a ground plane 40 and a dielectric 50 as in FIG. 1.Dimensions of one embodiment are shown in FIG. 2 by way of example. Theantenna structure 110 further includes coax cable connections 32 and 34for connection to a tag reader. In the example shown the thickness ofthe dielectric 50 is only 4 mm, which renders the antenna structure 110particularly flat. It can be mounted on the ground or a floor and, dueto its flat design, can easily be walked upon or driven over. Theantenna structure 110 shown in FIG. 2 could thus be used to control thepassage of any tagged goods through the doors of a supermarket or awarehouse.

In order to enable the antenna structure 110 of FIG. 2 to be walked uponor driven over, the three main components (patch antenna 20, groundplane 40 and dielectric 50) are made of a sufficiently strong material.The antenna structure 110 could also be covered or encased for addedprotection.

FIG. 3 shows a further use of the antenna structure 110. As shown inFIG. 3, the antenna structure 110 is attached to one of the rearportions 60 of the fork of a fork-lift truck. Again, the antennastructure 110 should be made sufficiently robust to resist any damage.

Common to all of the antenna structures 10 and 110 shown in FIGS. 1 to 3is the fact that the patch antenna 20 is electrically insulated from theground plane 40 by means of the dielectric 50. This renders thestructure particularly simple and hence enables manufacture at low cost.

FIG. 4 shows a YAGI type radio frequency identification tag antennastructure 200. This comprises a conventional RFID tag 210 placed above adriven rod 220. A reflector 240 (which is of the same length or greaterthan the driven rod 220) is arranged on one side of the driven rod 220,and one or more director elements 245 are arranged at the opposite sideof the driven antenna element 220. The driven element 220, the directorelements 245 and the reflector element 240 are all located in the sameplane. For proper tuning of the antenna structure 200 the spacingbetween the driven element 220 and the reflector element 240 and thedirector elements 245 can be determined empirically. The spacing maydepend on the material which fills the space between thedriven/reflector/director elements.

As indicated in FIG. 5, the structure of FIG. 4 can be incorporated intoan object 260 such as a plastic bucket or crate. FIG. 5 shows a crate260 in cross section. One or more of the driven antenna element 220, thereflector element 240 and the director elements 245 are moulded into theside-wall 265 of crate 260. In FIG. 5 only the reflector element 240 isshown. The driven antenna element 220 and director elements 245 arelocated “behind” the reflector element 240, i.e. behind the paper plane.The reflector element 240, the driven antenna element 220 and thedirector elements 245 form an integral part of the crate 260. The crate260 is also provided with holding protrusions 250 for receiving a RFIDtag 210. This, together with the driven antenna element 220, thereflector element 240 and the director elements 245 form a multi-elementantenna similar in construction to a YAGI antenna.

Instead of being provided externally, the RFID tag 210 could also beincorporated into the wall 265 of crate 260.

In an alternative embodiment (not shown) the side-wall 265 of crate 260includes a metallic ground plane 40 instead of the driven, director andreflector elements. A patch antenna 20 is either mounted on the surfaceof the side-wall 265 of crate 260, or moulded into the material of theside-wall 265 of crate 260. The material of the side-wall 265 betweenthe ground plane and the patch antenna effectively forms the dielectricmaterial 50 for the patch type antenna structure.

Referring now to FIG. 6, this shows a bi-directional multi-elementantenna structure similar in construction to a YAGI antenna structure.The basic structure is similar to that of the embodiment shown in FIG.4. However, instead of the reflector element 240 shown in FIG. 4, theFIG. 6 embodiment has two further director elements 245 opposite thosedirector elements 245 which are shown in FIG. 4. The antenna structureshown in FIG. 6 is suitable for radiating in both directions asindicated by bold arrows.

In some embodiments a RFID tag is provided which has a RFID tag modulecoupled to an antenna structure which is separate from, separable from,or arranged to be severable from the tag module.

FIG. 7 shows such an embodiment. This figure shows a tagged item 330, inthis example a shirt. The shirt 330 is arranged on a piece of cardboard320. A RFID tag module 300 is embedded in the collar 340 of shirt 330.In preferred embodiments the tag module is sandwiched between two layersof material of the shirt collar 340 so that it is not visible. A pieceof metal foil 310 (shown here in cross-hatching and) is attached to aportion of the cardboard 320, for example by means of an adhesive, suchthat it is located near the tag module 300. Part of the metal foil 310extends into the space between two folded portions of the collar, asindicated by a dashed line in FIG. 7. As long as the tag module 300 issituated near the metal foil 310 the metal foil acts as an antennastructure for the tag module 300, i.e. it is coupled to the tag module,e.g. by electromagnetic, inductive or capacitive coupling, i.e.non-contact coupling.

The metal foil 310 enables the tag to be communicated with (e.g. by aRFID reader) over a relatively large range, for example a few metres. Inthe preferred embodiment the tag module can be communicated with even ifit is not coupled to the metal foil 310. However, the range over whichit can be communicated with is much shorter than when it is coupled tothe metal foil 310.

FIG. 8 shows a modification of the embodiment shown in FIG. 7. Again, aRFID tag module 300 and a piece of cardboard 320 is shown. The shirt hasbeen omitted in FIG. 8. Cardboard 320 carries 3 strips of metal foil 310and 318 constituting a multiple-element antenna structure similar inconstruction to a YAGI antenna. Metal strip 310 is provided with a lip315 to facilitate coupling between tag module 300 and the antennastructure. The width w of the strips 310 and 318 is preferably, but notnecessarily, chosen to be λ/2, λ being the wavelength corresponding tothe operating frequency of the tag module. Good results are generallyachieved if the width w is an odd multiple of λ/2, although this is notessential. The spacing d between the multiple elements 310 and 318 ofthe antenna structure is preferably chosen to be λ/4 to λ/6, but this isalso not essential.

However, it is preferred that a dimension of the antenna structure orits elements is λ/2. FIG. 9 illustrates this. Shown is again a tagmodule 300 in coupling relationship with strips of metal foil 310 and318 as in FIG. 8. The length and width of the larger piece of metal foil318 is shown as 1 and w. One of these is preferably chosen as λ/2.

FIG. 10 shows an alternative embodiment. FIG. 10 shows a crate 350.Several antenna elements 312 (in this example metal rods) are embeddedinto the base of the crate, which are all equidistant and of the samelength. When an item (not shown) carrying tag module 300 is placed inthe crate 350 the tag module 300 is in coupling relationship with theantenna elements and thus forms a RFID tag. This tag can be communicatedwith over a larger distance than if the antenna structure formed by rods312 was not present.

As a modification, the crate could have its own tag module (not shown),preferably embedded, and either directly connected to one of the rods312 by means of a galvanic connection, or coupled thereto by means of anon-contact coupling. This modification enables communication with thecrate's own tag module and with the modules of any items placed withinthe crate 350.

FIG. 11 shows an alternative embodiment using a slot antenna 310 mountedto a side of a crate or container. The slot antenna 310 consists of ametal foil with a slot 316 extending vertically in FIG. 11, i.e. withpolarization extending horizontally. Two tagged items are placed withincrate or container 350, with their tag modules 300 and 301 beingarranged such that their polarizations extend horizontally, whichenables coupling between the slot antenna 310 and each of the tagmodules 300 and 301 for forming two RFID tags.

The FIG. 11 embodiment works well if, as shown, the polarization of thetag modules 300, 301 is “sufficiently parallel” to the polarization ofthe antenna structure 310, but it may not work if this condition is notsatisfied. FIGS. 12 and 13 show antenna structures which address thisproblem. FIG. 12 shows an antenna structure with two antenna elements(slot antennas) 310 and 311, whose polarizations are perpendicular so asto be able to couple with a tag module regardless of its polarizationorientation.

FIG. 13 schematically shows an antenna structure consisting of amultidimensional wire 310, i.e. wire 310 is not straight over its entirelength. The fact that its ends are bent at right angles with respect tothe middle portion of the wire means that its ability to couple with tagmodules of a variety of polarization orientations is improved.

The FIG. 12 and FIG. 13 embodiments also improve the ability of a tagreader or similar to communicate with the tag module in multipledirections, i.e. in the case of a crate having an antenna structure asshown in FIG. 12 or 13 and passing through e.g. a door with RFID reader,it does not matter in which orientation the crate passes through thedoor. In other words, with these embodiments more directions arecovered, not only as regards the coupling between the antenna structureand any tag modules, but also as regards communication between a RFcommunication means (such as a RFID reader) and the antenna structure orany tag modules (via the antenna structure).

FIG. 14 shows an embodiment in which the antenna structure 310 isinitially connected to the tag module 300. The tag module 300 (the lowerhalf of the device shown in FIG. 14) comprises an electronicidentification circuit 305 and a conductor 308 coupling the circuit toantenna structure 310. Conductor 308 thus forms a contact couplingbetween the antenna structure 310 and the circuit 305. A preferred lineof fracture 309 such as a weakness in the plastics material encasing thetag module 300 and the antenna structure 310 is provided. The antennastructure 310 can easily be severed from the tag module 300 by breakingalong the weakness 309. Once the tag has been severed the tag modulecannot be communicated with by RF communication means (such as a RFreader). However, the tag module can be communicated with by connectinga suitable reader to the ends of conductor 308 by a galvanic connection.

The material of the conductor 308 can also be weakened at the preferredline of fracture 309.

FIG. 15 shows a modification of FIG. 14. In FIG. 15 the tag module 300comprises an identification circuit 305 and an “internal” antenna 306 ofshort range. This “internal” antenna is connected to circuit 305 by agalvanic connection, or could be formed as integral part of circuit 305.The circuit 305 is not connected to antenna structure 310 by a galvanicconnection. Instead, “internal” antenna 306 is in (non-contact) couplingrelationship with “external” antenna structure 310, which effectivelyincreases the range over which the tag module 300 can be communicatedwith. A preferred line of fracture 309 is again provided, along whichthe tag module 300 can be severed from antenna structure 310. Aftersevering the tag module 300 can still be communicated with, however onlyover a relatively short range.

Although the invention has been described in terms of preferredembodiments as set forth above, it should be understood that theseembodiments are illustrative only and that the claims are not limited tothose embodiments. Those skilled in the art will be able to makemodifications and alternatives in view of the disclosure which arecontemplated as falling within the scope of the appended claims. Eachfeature disclosed or illustrated in the present specification may beincorporated in the invention, whether alone or in any appropriatecombination with any other feature disclosed or illustrated herein.

1. An object, comprising: an antenna structure that is separate from,separable from or arranged to be severable from a radio frequencyidentification tag module that has a communication range, wherein: theantenna structure is configured to increase the communication range ofthe radio frequency identification tag module; and the antenna structureis incorporated in material of the object.
 2. The object of claim 1,wherein the antenna structure includes a ground plane made from aflexible material.
 3. The object of claim 2, wherein the flexiblematerial is a metallic mesh incorporated in the material of the object.4. The object of claim 2, wherein the flexible material is a foilincorporated in the material of the object.
 5. The object of claim 2,wherein the antenna structure includes a patch antenna spaced apart fromthe ground plane.
 6. The object of claim 5, wherein the patch antenna iselectrically isolated from the ground plane.
 7. The object of claim 2,wherein the object is a piece of clothing.
 8. The object of claim 1,wherein the material serves a second function for the object, the secondfunction being different than and in addition to an antenna functionserved as the antenna structure.
 9. The object of claim 1, wherein theantenna structure is molded in the material that forms the object. 10.The object of claim 1, wherein the object is a crate.
 11. The object ofclaim 1, wherein the antenna structure includes a reflector/directorelement.
 12. The object of claim 1, wherein the antenna structureincreases the communication range of the radio frequency identificationtag module from less than a meter to more than a meter.
 13. A method ofcommunicating with a radio frequency identification tag module,comprising: providing the radio frequency identification tag module thatis separate from or has been severed from an antenna structure;connecting a reader to the radio frequency identification tag module;and communicating with the radio frequency identification tag module.14. The method of claim 13, wherein connecting the reader to the radiofrequency identification tag module includes forming a contact couplingbetween the reader and the radio frequency identification tag module.15. The method of claim 14, wherein forming the contact couplingincludes forming a galvanic connection coupling between the reader andat least one conductor of the radio frequency identification tag module.16. The method of claim 14, wherein the at least one conductor of theradio frequency identification tag module is configured to couple withthe antenna structure that is separate from or has been severed from theradio frequency identification tag module.
 17. A reader configured tocommunicate with a radio frequency identification tag module,comprising: a connector configured to couple to the radio frequencyidentification tag module that is separate from or has been severed froman antenna structure; and a processor configured to communicate via theconnector to the radio frequency identification tag module.
 18. Thereader of claim 17, wherein the connector is configured to contactcouple with the radio frequency identification tag module that isseparate from or has been severed from the antenna structure.
 19. Thereader of claim 18, wherein the connector is configured to contactcouple to a portion of the radio frequency identification tag modulethat is or was configured to couple to the antenna structure.
 20. Thereader of claim 17, wherein the connector is configured to non-contactcouple to an internal antenna of the radio frequency identification tagmodule that is separate from or has been severed from the antennastructure.